Wire electrical discharge machining apparatuses can cut tapers by tilting the wire electrode. Conventional techniques are known that provide correction for the amount of taper angle in accordance with the taper angle (see Patent Literature 1 and Patent Literature 2, for example). Another technique is also known that corrects for errors in a taper angle that occur due to the clearance of the wire guide, by correcting a command movement vector of a machining axis or a taper axis on the basis of the amount of clearance of the wire guide (see Patent Literature 3, for example).